Rivista Italiana di Paleontologia e Stratigrafia volume luz numero 1 pagrne 131 134 Aprile 1996 NOTE BREW AN EXCEPTIONAL REPTILE FIND IN THE NORIAN (LATE TRIASSIC) LAGERSTÀ.TTE OF ENDENNA (ZOGNO, BERGAMO, ITALY) ANDREA TINTORI, SILVIO RENESTO, CRISTINA LOMBARDO, GIANLUCA MANAROLLA. MATTEO MANENTI & MASSIMILIANO VENDiCO K^,-",,^.).. p--r;li. Norian (Late Triassic), Calcare di zorztno, Lombardy Q.tronhern Italy), new find. Riassunta" Durante un sopralluogo nella località di Endenna (Zogno, BG) il 5.10.95 è stato rinvenuto un frammento di un grande rettile parzialmente danneggiato da scavatori abusivi. Dopo il salva- taggio del blocco già isolato, si è proweduto alla ricerca e al recupero della rimanente pane dell'esemplare. Durante questi lavori sono an- che stati sorpresi alcuni scavatori abusivi che sono stati segnalati alla competente Soprintendenza. Il rettile si presenta completamente in- globato in matrice calcarea molto tenace e si prefigura parzialmente arrotolato e con il cranio disarticolato rispetto al resto del corpo. La hnghezza totale supera i 4 m e 1o stato di conservazione è da ritener- si ottimo. Sulla base di osservazioni preliminari si può ipotizzare 1a sua àppar-tenenza all'ordine Thalattosauria. Si tratterebbe quindi del pitì grande rettile acquatico triassico, con I'esclusione degli ittiosauri, finora conosciuto. Abstract. Durìng a survey àt the fossiliferous site of Endenna (Zogno-Bergamo) of Norian age, a huge reptile has been found at Oc- tober the 5th, 7995. The recovery of the whole specimen took place at the beginning of November. Four main blocks, plus minor fragments, are now in the laboratory of the Department of Eanh Sciences of the Milano University waiting for the long prepararion. The specimen is somewhat more than four meters long, the head being disarticulated in front of the body. A preliminary survey suggesrs the reptile may be ascribed to Thalattosauria. thus, apart from the ichthyosaurids, it would be the largest marine reptile of the Triassic. The find. The fossil-site of Endenna (Zogno, Bergamo, Italy) is one of the most important sites in the Calcare di 7nr- zíno (Zorzino Limesrone) (Tintori et a1., 1985). Vith the permit of the Soprintendenza Archeologica della Lombardia and under the direction of the senior author, field-works were carried our from 1978 unttl 1983, when works v/ere stopped for logistic causes and started in the nearby Zogno2 locality. Nonetheless, regular sur- veys are necessary because private collectors frequently damage the site, anything but exhausted. A couple of them have been catched during the recent works and reported to the competent aurhority. Hundreds of fishes have been collected during six years of digging (Beltan & Tintori, 1980; Tintori, 1980, 198t, 1983, !99Q, 199L, 1992, 1995; Tintori & Renesro, 1983; Tintori & Sassi, t992), together wirh some reptiles (Padian, 1981; Pinna, 1,979,1,980, 1984;Pinna 6c Nosot- ti, 1989; Renesto 1.984, 1992, 1,993,1994a,b, c, t995a,b; Renesto & Tintori, 1995) and several, mostly undescri- bed, invertebrates (Basso & Tintori, 1994). On the last 5th of October, the senior author was accompanying Dr. W. Bausch (Erlangen, Germany) to a survey for geochemical sampling in Endenna. He found a block, measuring about 80x40 cm (block n.3) which showed remains o{ a very large organism, possibly a rep- tile. Coming from level 11 (Tintori et al., 1985), the block had been removed and damaged by unauthorized diggers. In this case, splitting was difficult because the big fossil has disturbed the regular lamination and has caused a locally stÍonger cementation. The relative posi tion between the block and the resr of the layer was difficult to state, but the possibilities that at leasr part of the fossil rvas stiil in place were good. The problem was that the find was close to the end of the fossillevel outcrop, so we wondered how much of the fossil had been already destroyed by natural erosion. The block was taken to Milano only a few day after and, by the end of October, we organized the reco- ver of the rest of the fossil. It rook rwo davs of work (the 3Oth of October and the 2nd of Norre-t".) for six people, but we had the greatest expected success: the re- main of the reptile was still in place and could be com- pletely removed. Closely observing the front of layer 11, we could see that the reptile was in its lower parr. The upper part 'was then removed; the underlying thin, shaly level made the rest of the fossiiiferous level easy to take off. Taking advantage oÍ a lateral small karstic canai (KC in Fig. 1) and natural fractures the caudal region (Fig. 2) Milano, via Mangiagalli 34,2a1.33 Milano, Italy.- Dipanimento di Scienze della Terra dell' Università degli Studi di 132 A. Tintori, S. Renesto, C. Lombardo, G. ManaroLla, M. Manenti & M. Vendico ll{{ has been evidenced on the upper surface of a slab (Fig.1; block +) measuring about 140x105 cm. The rest of the fossil was more problematic to recover: the fracture be- tween blocks 2 (60x50 cm) and 1, (75x30 cm) was irregu- lar, leaving a couple of small fragments in between. On the whole, the reptile has suffered very little damage. The total weight of the blocks is about 250 kg; they have been trasported for about 1 km on hand-barrow up to the car. Shape and dimension of the skeleton can be gues- sed trough the sediment covering the fossil. A part of the posterior leg (knee arriculation) has been already prepared, to help in a preliminary classification. The ob- servation of the fossil suggesrs that the reprile has long trunk and tail, relatively short legs and considerably long skull. Its total length should be more than 4 m. The body, lying on its belly, forms an almost complete circle (Fig. 1). All these features indicate the skeleton does not belong to an ichthyosaur; in fact, femur, tibia and fibula, showing sharp epiphyses and narrow diaphy- ses, are very different from those of Ichtyosaurs. On the basis of the same morphologic features we can exclude the fossil belongs to the nothosaurs, which have shorrer tail, longer neck and smaller skull. Leaving apan rhe ichthyosaurs, to nothosaurs belonged the largest known acquatic reptiles in the Triassic, before this find. A spe- cimen of Paranothosaurus atnsleri from the Ladinian of Monte San Giorgio (Canton Ticino, Switzerland) rea- ches 3.80 m and it was the largest one, as far as we know. Triassic phytosaurs seem to show more similarities with the new find. They are crocodile- like archosaurs with nostrils back near the eyes. Phytosaur remains are known from Upper Triassic in Germany, in USA and in India and fragments are found also in several sires of the Middle and Far East. Phytosaurs are thought ro have dwelled in continental environments, such as lakes and alluvial plains, and to have very rarely visited marine y/aters. This is clearly in contrasr with the fossilization environment of the Caicare di Zorzíno, which is an in- traplatform basin with only small islands nearby (|adoul et a1., 1994; Renesto & Tintori, 1995; Tintori, 1995). Nonetheless, an isolated skull of a phytosaur had been already found in Endenna, but it is probably a fragmenr of a floating skeleton coming from dry land (Renesto, 1995b). The new specimen cannot have been transpor- ted: its skeleton is complete and perfectly articulated, apart from the skull. Moreover, though the relative di- mensions of the skull are comparable to those of phyto- saurs, other features have different proportions: tail, for example, is too long. Only a last group of reptiles can be compared with the new, large specimen: Thalatto- saurs. These are possibly archosauromorph reptiles char- acterized by relatively short legs and long, laterally com- pressed tail. Thalattosaur remains are known from the Middle Triassic of the Formazione di Besano (Grenzbitumenzo- ne for the Swiss authors) and of California and from the Upper Triassic of British Columbia. Aiso Endenna have yielded two specimens of Endennasaurus (Renesto, 1984, 1992). Thalattosaurs lived in strictly marine environ- ments (fossils are often associated with ichtyosaurs and ammonites) and they likely had a semi-durophagous diet. Proportions of the new reprile are well comparable \*" \ Fig. 1 - Schematic draw of the four blocks with the probable repti- le outline (dotted area, in black the already exposed poste- rior leg) as seen from above. KC: karstic canal; S: slum- ping like deformation of the underlying laminae beside the specimen belly; striped area: empry region. We expect the preparation will rake a very long time: on the lower side, apparently the easiest, at least 18 months are necessary to expose the bones. Flowever, it will be convenient to expose the fossil on both sides, at least in important parts, because it is fortunately very slightly compressed; even the head is tridimensionally preserved. 3D conservation is rarely found in our No- rian locaiities and only regards parts of large specimens with strong structures (the skull of Mystriosuchus and the mouth region of large Sargodon tomicu). Normally, fossils are totally flattened and bones are more or less broken by lithostatic pressure. Taphonomic and systematic remarks. The impact of the reptile body on the bottom compressed the underlying laminae, inducing also a uni- derectional slumping-like deformation for at least 1 m from the body itself (S in Fig" 1); this fa*, together with the absence of further compression of the skeleton, suggests that diagenesis in this level has been remarka- bly early. Laminae in fact, show folds which keep their individuality. An accurare sedimentological-geochemical study on those laminae is trying ro undersrand the first diagenetic stages in an anoxic environmenr with predo- minant carbonatic sedimentaticn. Exceptional repttle find tn Endenna Fig. 2 - The slab (block 4 in fig. 1) with the tail. Scale-bar: 15 cm to those of thalattosaurs and their life environment is in agreement with the paleoenvironmental reconstruction of the Calcare di Zorzrno. In conclusion, for the classification of the new reptile specimen, three hypotheses can be put forward, with decreasing likelihood: it is a new genus of thalatto- saur, it is a phytosaur or it is a totally new organism. In any case, this new find will through new light on rhe life environment of the Zorzino fauna: before this, no very large reptile had been found. This fact was explai- ned with the presence of geographical and ecological barriers for both marine and terrestrial organisms, which favoured the rising of an endemic reptilian fauna made of mainly small species. Now we must reconsider that, or suppose that those infraplatform basins were so rich in iife that aiso large organisms could develop and be sustained. Acknouledgements, Thank are ciue to the Soprintendenza Archeologica della Lombardia which gave us the special permission ro recover the specimen. The picture is by G.Chiodi. 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